Flammable vs. inflammable

There is no difference in meaning between flammable and inflammable. Both describe things that are capable of burning or easy to ignite, but in all modern varieties of English, flammable is preferred.

Inflammable, derived from the verb inflame, is the original word. But because the first syllable is easily misinterpreted as the common negative prefix in- (as in, for example, inescapable, invulnerable, inorganic), the word has always caused confusion. Because this confusion can have dangerous real-world consequences, the shift from inflammable to flammable is welcome.

The less confusing flammable did not enter common use until the early 20th century, but it quickly became the prevalent spelling. Inflammable is still common on product labels and appears from time to time in edited publications, but it fell out of favor around 1970.

This ngram graphs the use of flammable and inflammable in English-language books published from 1800 to 2019.

Flammable Vs Inflammable English

4 thoughts on “Flammable vs. inflammable”

  1. Definitely *flammable*; confusion in this case can be indeed dangerous. Not dangerous but annoying: “balance” vs. “balance”:

    balance: Your account balance is the amount of money you have in one of
    your financial accounts. For example, your bank account balance refers
    to the amount of money in your bank accounts. / Your account balance can
    also be the amount of money outstanding on one of your financial
    accounts. Your credit card balance, for example, refers to the amount of
    money you owe a credit card company.” When Verizon tells me my balance
    is over $200 — as they just did — is that what I have on account or what
    they want me to pay up? Given that they kept texting me about it and
    told me when and where to send them money, it could’ve been that I owed
    them money; as it happens (long and boring story omitted here), they, so
    to speak, owe me.

  2. For the record: I was once told by a chemist that “flammable” and “inflammable” have distinct meanings. “Flammable,” he said, means, capable of burning (i.e., of being fuel for combustion, of catching on fire). “Inflammable” means tending to burst into flame. Whether historical use, by scientists, of the two words supports that, I don’t know.

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